Steel



Patented Apr. 19 1927.

UITED STATES OTTO PATTERMANN, OF KLADNO, CZECHOSLOVAKIA, ASSIGNOR TO POLDIH'U'TTE, OF PALACKEHO TRIDA, PRAHA-VINOHRADY, CZECHOSLOVAKIA, A JOINT-STOCK COMPANY.

STEEL.

No Drawing. Application filed January 29, 1926, Serial No. 84,754, and in Germany January 8, 1925.

Tools and constructional parts which must be of high strength and tenacity and must retain these properties at high working temperatures, such as dies, swages, valves for high temperature explosion-motors, valvesprlngs for service with superheated steam,

parts of fire arms and the like, are frequently produced from chromium-tungsten steel. In so far as this steel is considerably alloyed, it is not tenacious enough for many .purposes and, moreover, a complicated heat treatment of objects manufactured therefrom is necessary. Less considerably alloyed chromium-tungsten steel, While easier to treat, losesits strength and becomes soft at high working temperatures.

According to the invention, a steel suitable for objects employed at high temperatures and answering all requirements in a most satisfactor manner is produced by the addition of nic e1 to a chromium-tungsten steel containing at least 3% tungsten. The new steel is hard and tenacious, retains its strength at high temperatures and, moreover, presents no difficulties in the heat treatment during the manufacture of the objects.

The following composition is given as an example of the new steel:

' Per cent. Carbon 0. 3 Chromium 3. O Tungsten 10.0 Nickel 3. 0

The following steel was employed heretofore as the best steel for the range of applications mentioned:

Per cent Carbon O. Chromium 3. 0 Tungsten 10. 0 Vanadium 0. 3

This st eel exhibits a good notched bar impact-test value only on being tempered at a temperature between narrow limits, namely 620660 C. The strength, however, falls considerably due to this tempering alone. The narrow limits for the tempering temperature are dilficult to, observe.

' The steel according to the invention is, on

the other hand, tempered to a blue colour 390 C. only, an operatmn which can be car ried out easily and reliably in the Workshop. From the tollowmg comparison it is clear that the new steel is, In respect of strength and tenacity, superior to the above given chronnuni-tungsten steel.

; Notch (1 Type. llard- 'lcm- I Tensile Elon- Egg: bar Dismal nned pcred limit strength gatlon on impact tat- ,kg/mm 7 test i mkg/cxn Chromi-1,200C. 660C-. 128.0 140.8 7.5 54.8 7.2

um in oil. I tungl sten I steel. 1 New 11 330 C 146.3 167.5 8.5 42.6 9.2

steel. blue colour 11.3 JERTSE SEEBT.

The notched bar impact-tenacity (work of fracture) is determined on bars of cross section 20 X 160 mm, with a 4. mm. wide, 5 mm. deep semicircular notch, the distance of the supports being 120 mm., by means of 75 ink". Charpy-pendulum impact apparatus.

Alloying metals having an improving ell'ect, other than chromiiun, tungsten and nickel, such as vanadium, may, according to l'l in enti n, be added to the steel. Further, the tungsten may be wholly or partially replaced by molybdenum, which has the same effect, and the nickel by cobalt.

lVhat I claim is:- V 1. A special steel comprising 10% tungsten, 3% chromium and 3% nickel.

2. A special steel comprising 10% tungsten, 3% chromium, 3% nickel and .3%

or'ro PATTERMANN. 

